Kaede from Shuffle. When I saw her go nuts she looked like she could go school days on your ass.

Shame, because I absolutely loved her motherly figure in the house and was very cute. Felt very sorry for her when her feelings were ignored throughout the series, but then you realize later the pic above wasn't the first time she looked like that and why.

I mean srsly, Izaya swings around a knife and laughs hysterically all the time while doing completely unexpected crazy things 24/7. Then there's Shizuo with his uncontrollable anger and tendencies to throw vending machines and other objects at people. (He should know the problems aren't going to go away just by throwing vending machines at it... It's just like Mako Tsunami and his harpoon problem. Tsk tsk.)

That should fall under the lines of psychopathic under some extent, right?